1) Field of the Invention
The present invention relates to a terminal apparatus, a controlling method for optical output power and a computer-readable storage medium having an optical output power controlling program stored thereon, suitable for use where a wavelength is newly extended in an existing optical transmission system such as, for example, an optical submarine cable system which utilizes an optical amplification submarine repeater.
2) Description of the Related Art
In recent years, extension of a new wavelength is carried out for an existing optical transmission system such as, for example, an optical submarine cable system utilizing a wavelength division multiplexing (hereinafter referred to as WDM) method.
In order to extend a new wavelength, it is necessary to adjust the optical output power (optical transmission power) of an optical signal having a wavelength to be newly extended.
In this instance, in the WDM optical transmission system, where a code error correction (Forward Error Correction; hereinafter referred to as FEC) processing section is provided on the receiving side, it is generally the case that a code error rate (Bit Error Rate; hereinafter referred to as BER) is calculated for each of wavelengths based on an error count counted by the FEC processing section and results of the calculation are fed back to the transmitting side so that the optical output powers of the wavelengths are individually adjusted on the transmitting side (refer to, for example, Japanese Patent Laid-Open No. 2002-57624). Such control of the optical output powers as just described is called pre-emphasis (hereinafter referred to as PE) control.